If Delhi was Beijing, it would shut 29 of 30 days

When air pollution hits a certain danger mark in Beijing, the government issues a red alert that automatically puts curbs on factories, construction work and vehicles. If Delhi had a similar system, then almost right through November, the stipulation on cars with odd- and even-numbered license plate using the roads on alternate days would have been in force. Schools and factories would also have remained shut for the entire month.

According to an analysis by Greenpeace India and East Asia, on 29 out of November's 30 days, the quality of air in Delhi was so poor that a smog alert should actually have been declared, as in Beijing, and emergency measures imposed to bring the severity down. Greenpeace extrapolated data from the Central Pollution Control Board's air quality index (AQI) to identify the days in November that breached the benchmark for a pollution alert under the Chinese system.

In the 91 days between September and November, Delhi hit the red mark as many as 33 times. In the same period, Lucknow had 40 poor days. "The problem is not limited to Delhi, as several other cities across North India faced similarly high levels of pollution," said the Greenpeace statement on Thursday.

According to the organization, a red alert is sounded in Beijing when there is the likelihood that an AQI of 200-which indicates the presence in the air of around 350 microgram per cubic metre of PM10 (coarse pollution particles)-will linger on for more than three consecutive days. In the Indian AQI system, such a level would be reached at a score of 300.

Beijing counters pollution at four levels, red being the most dangerous. At that point, power plants are directed to cut emissions, factories are shut down, schools are closed and only odd- or even-numbered cars are allowed to ply on alternate days to take half the vehicular population off the roads.

"Beijing issued its first formal red alert on December 8, entailing very strict measures to curtail pollution emissions from factories, vehicles, construction and other activities, as well as closing down schools to protect students," said Lauri Myllyvirta, Global Campaigner, Greenpeace East Asia.

Myllyvirta said these measures helped mitigate the impact of the event. In the three days after the alert, the Chinese capital's air quality has improved dramatically, according to residents and government spokespeople there.

The China Environment Protection Bureau reported an air quality index of 37 at 9 pm on Thursday. The AQI was less than 100 for most of the day after hovering around a whopping 300 on Wednesday.

In Delhi, Thursday's AQI was 350, which is defined as "very poor" under the Indian AQI system. The AQI at RK Puram at 9 pm was 426 (severe), while that at pollution hotspot Anand Vihar was identical at 426.